iOS传感器开发之——手势识别

一.手势种类

在iOS中常用的手势分为两种，一种是Touch事件，一种是继承于UIGestureRecognizer的手势识别类来识别。

在iOS中只有继承自UIResponder类的对象才能处理手势事件。

触摸事件

Touch事件一般由以下几个方法来处理事件

//触摸开始
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;
//触摸移动
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;
//触摸结束
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;
//触摸取消，一般为非人为的触摸停止，如接入电话
- (void)touchesCancelled:(nullable NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;

使用Touch事件直接在相关视图类中重写以上方法即可

需要注意的事：

1.该类必须直接或者间接继承UIRespender

2.必须重写touchesBegan:withEvent:方法

3.视图的userInteractionEnabled属性必需是YES

4.视图的hidden属性必须不为YES

5.视图的透明值必须大于0.01

在以上方法中我们通过参数touches可以获得所有的UITouch值，UITouch用于存放你触摸事件。

//通过该方法从UITouch对象中获得位置信息。
//参数view是相对于哪个视图的位置，一般使用self
- (CGPoint)locationInView:(nullable UIView *)view;

 

下面是一个手指画线的Demo

#import "MyDrawView.h"
@interface MyDrawView (){
    CGPoint        _beginDrawPoint;
    CGPoint        _moveDrawoint;
}
@property (nonatomic, retain) NSMutableArray *lineAllArray;//储存所有线
@property (nonatomic, retain) NSMutableArray *pointAllArray;//储存所有点
@end

@implementation MyDrawView


#pragma mark - 初始化数据
#pragma mark 初始化点的数组
- (void)initMyPointArray {
    self.pointAllArray = nil;
    self.pointAllArray = [[NSMutableArray alloc] initWithCapacity:0];
}

#pragma mark 懒加载初始化线数组
- (NSMutableArray *)lineAllArray {
    
    if (_lineAllArray == nil) {
        _lineAllArray = [[NSMutableArray alloc] initWithCapacity:0];
    }
    return _lineAllArray;
}

#pragma mark 插入点到点数组
- (void)insertToPointArrayWithPoint:(CGPoint)sender {
    
    NSValue *pointValue = [NSValue valueWithCGPoint:sender];
    [self.pointAllArray addObject:pointValue];
}

#pragma mark 插入所有点到线数组
- (void)insertToLineArrayWithPointArray{
    
    [self.lineAllArray addObject:self.pointAllArray];
}


#pragma mark - Touch事件
//手指开始触屏开始
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    //从touches集合中拿到被触摸的点
    UITouch* touch=[touches anyObject];
    _beginDrawPoint = [touch locationInView:self];
    //初始化数组并插入点
    [self initMyPointArray];
    [self insertToPointArrayWithPoint:_beginDrawPoint];
}
//手指移动时候发出
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    //从touches集合中拿到被触摸的点
    NSArray *movePointArray = [touches allObjects];
    _moveDrawoint =[[movePointArray objectAtIndex:0] locationInView:self];
    [self insertToPointArrayWithPoint:_moveDrawoint];
    [self setNeedsDisplay];
}

//当手指离开屏幕时候
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    //在完成绘画时讲所有点存入线数组
    [self insertToLineArrayWithPointArray];
    [self setNeedsDisplay];
}


#pragma mark - drawRect方法
- (void)drawRect:(CGRect)rect {
    
    //获取绘画上下文
    CGContextRef context=UIGraphicsGetCurrentContext();
    //设置笔冒
    CGContextSetLineCap(context, kCGLineCapRound);
    //设置画线的连接处　拐点圆滑
    CGContextSetLineJoin(context, kCGLineJoinRound);
    
    
    //绘画之前的线
    if (self.lineAllArray.count != 0) {
        [self drawRectBeforeLineWithContext:context];
    }
    //绘画之前的线
    if (self.pointAllArray.count >1) {
        [self drawRectCurrentLineWithContext:context];
    }
    
}

#pragma mark 绘画之前的线
- (void)drawRectBeforeLineWithContext:(CGContextRef)context{
    for (NSInteger i = 0 ; i < self.lineAllArray.count; i++) {
        NSArray *pointArray = [NSArray arrayWithArray:self.lineAllArray[i]];
        [self drawRectLineWithContext:context withPointArray:pointArray];
    }
}

#pragma mark 绘画当前的线
- (void)drawRectCurrentLineWithContext:(CGContextRef)context {
    [self drawRectLineWithContext:context withPointArray:[NSArray arrayWithArray:self.pointAllArray]];
    
}

#pragma mark 绘画线
- (void)drawRectLineWithContext:(CGContextRef)context withPointArray:(NSArray *)array {
    //绘画开始路径
    CGContextBeginPath(context);
    //获得开始点
    CGPoint startPoint = [array[0] CGPointValue];
    //开始绘画点
    CGContextMoveToPoint(context, startPoint.x, startPoint.y);
    //绘画结束点
    for (NSInteger j = 1; j < array.count; j ++) {
        //获得结束点
        CGPoint endPoint = [array[j] CGPointValue];
        CGContextAddLineToPoint(context, endPoint.x, endPoint.y);
    }
    
    //绘制画笔的宽度
//    CGContextSetLineWidth(context, font);
    //绘制画笔的颜色
//    CGContextSetStrokeColorWithColor(context,[color CGColor]);
//    CGContextSetFillColorWithColor (context, [color CGColor]);

    //闭合路径
    CGContextStrokePath(context);
}
@end

 

手势识别

在iOS常用的有以下六类手势

手势	作用
UITapGestureRecognizer	点击手势
UIPinchGestureRecognizer	捏合手势
UIPanGestureRecognizer	拖拽手势
UISwipeGestureRecognizer	轻扫手势
UIRotationGestureRecognizer	旋转手势
UILongPressGestureRecognizer	长按手势